/*
 * Copyright 2016 Carlos Ballesteros Velasco
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package java.security;

import java.nio.ByteBuffer;

public abstract class MessageDigestSpi {
	protected int engineGetDigestLength() {
		return 0;
	}

	protected abstract void engineUpdate(byte input);

	protected abstract void engineUpdate(byte[] input, int offset, int len);

	public static int getTempArraySize(int len) {
		return 0x100;
	}

	protected void engineUpdate(ByteBuffer input) {
		while (input.hasRemaining()) {
			engineUpdate(input.get());
		}
	}

	protected byte[] engineDigest() {
		byte[] out = new byte[engineGetDigestLength()];
		try {
			engineDigest(out, 0, out.length);
		} catch (DigestException e) {
			e.printStackTrace();
			return new byte[0];
		}
		return out;
	}

	abstract protected int engineDigest(byte[] buf, int offset, int len) throws DigestException;

	protected abstract void engineReset();

	native public Object clone() throws CloneNotSupportedException;
}
